Sprinkler base



FIG. 1 is a top plan view of a sprinkler base showing my new design;

FIG. 2 is a side elevational view thereof, the opposite side being a mirror image of the side shown;

FIG. 3 is a front end view thereof;

FIG. 4 is a rear end view thereof, and

FIG. 5 is a bottom view thereof. 

The ornamental design for a sprinkler base, substantially as shown and described. 